The present invention relates to a data processing system and a data processing method for appropriately synchronizing transactions to be executed at several machines connected to a network.
Database systems for real-time monitoring and controlling of data shared by computers distributed over a network have to process (search and update) a huge amount of data at a high speed. Such database performance thus depends on data-management systems that provide a means of accessing those data. Enhanced data-management systems could manage all data on a main-memory area, which are usually stored on an external storage device such as a hard disk. Increased storage capacity for main memories has allowed all data to remain in a main-memory area as resident data even in the present hardware environments.
Mere caching of a data-managing system on a main-memory area to known external storage devices cannot achieve high performance for real-time applications. There are two reasons for such a drawback: (1) a huge amount of data has to be transferred between an application and a data-managing system; and (2) execution of algorithms designed for disc storage devices on a main-memory area of each computer cannot achieve high performance. In addition, limited functions of such algorithms designed for disc storage devices and provided by a data-managing system cannot lighten loads for development of applications, nonetheless achieving high-speed processing a little bit.
Moreover, known data management systems have drawbacks discussed below.
Each application has a data-monitoring program for periodically monitoring data in the known systems. The period of watching data alteration is set at each application. It is thus impossible to set an approriate data-monitoring period over several applications, so that alteration made to data cannot be detected immediately. This forces each application to check whether data alteration has been made. Furthermore, each application must have a specific program that will start in synchronism with data alteration.